Method of determining proportions in compositions of substances



Oct. 7, 1952 G. H RZOG METHOD OF DETERMINING PROPORTIONS IN COMPOSITIONSOF SUBSTANCES Filed June 20, 1950 AMPL/F/e I m Patented Oct. 7, 1952METHOD F DETERMINING PlROPORTIONS` IN COD/[POSITIONS 0F SUBSTANCESGerhard Herzog, Houston, Tex., assignor to The Texas Company, New York,N. Y., a corporation of Delaware Application June 20, 1950, Serial No.169258V This invention relates to a method of measuring or controllingthe proportions or ratio of two substances in a composition of thosesubstances and it is the principal object of the invention to provide amethod of this kind by means of which accurate determinations can bemade ofthe proportions of two substances in a composition regardless ofthe form of the composition, i. e., ref gardless of whether it is amixture, a solution, emulsion, suspension or a chemical combination andwithout the necessity of any deformation of the composition, if a solid,and without access to the interior ofthe vessel or pipe containing thecomposition, if in the form of a fluid.

This is a division of my copending application Serial No. 574,135, ledJanuary 23, 1945.

Many difficulties are encountered in connec tion with the determinationor measurement of the proportions of two substances in a compositionwhere access 4is not readily obtainable to the interior of the vessel orpipe holding the composition. Again, where the composition is in the 5Claims. (Cl. .E50-43.5)

form of, say, a sample of a solid it is very diiiicult A to determinethe proportions of the constituents without removing a portion of thesample or otherwise disguring or deformingthe sample in order to makethe analysis. As an example, let us assume that a composition is formedof two substances either in a homogenous or a nonhomogeneous mixture andin the form of, say, a block or a brick. Without removing a portion ofthe block for chemical analysis, it would obviously be difficult todetermine the proportions of the two substances. As another example,suppose that a fluid is ilo-wing through a pipe and that the fluid isformed of `two substances the ratio of which it is desired to ascertain.Without removing a sample of theilowing fluidfor analysis by weighing orby chemical means, it would obvious-l ly be diicult to determine theexact ratio of the two substances forming the fluid. It would be stillmore diflicult to, make a continuous record showing substantiallyinstantaneously variations in the ratio of the two iiuids withoutcontinuously removing or by-passing a small amountgof the fluid to beused for analysis. Y

In accordance with the present invention a method has been devisedthrough the use of which the desired results mentioned above, i. e.,

measurement or control oi the proportions of substancesin a composition,can be obtained, and this regardless of the form of the composition, i.e., whether it is asolid or a fluid mixture, a solution, emulsion,suspension or a chemicalcombination. Through the use of the `inventionit is also possibleto determine variations inptemperature which mayoccur in the composition, such as a fluid owing through apipe,"withou tremoving samples and without any access to the interior o1' the pipe forthe insertion of thermocouple elements, or the like.

In carrying out the invention, a beam of penetrative radiation istransmitted through the composition, the proportionsof which it isdesired to ascertain and a mea-surement is made of the intensity of theradiation after it has traversed the composition. The length of the pathof the beam through the composition may be selected so that apredetermined accuracy can be obtained, Thus, the beam may passdiagonally through a pipe carrying a fluid composition or it may passthrough a selected portion of a vessel in which the composition is beingtreated. By proper calibration of the measuring instrument, theintensity reading can be made to indicate directlythe ratio of the twosubstances in the composition be-v ing examined. For calibrationpurposes a measurement as described above can be made where the beam ofradiation is transmitted through each of the substances separatelyproviding that the length of the path of the beam through the substancesis the same as in the case where the beam is transmitted through themixture or composition. If desired, instead of measuring the intensityof the radiation passing through each of the substances taken alone,measurements-can be made through known mixtures, i. e., compositionswherein the proportions o-r the ratio of the two substances are known,and a calibration curve then prepared from which the ratio of thesubstances in an unknown composition can subsequently be read directly.

As an example of an application of the invention a description will begiven of the use of the method as applied4 in determining the ratio ofacid catalyst to hydrocarbons in an alkylation process` Vwhereinisoparafnic hydrocarbons are alkylated vto produce hydrocarbons suitablefor an aviation type motor fuel.

For a better understanding of the invention reference may be had to theaccompanying drawing in which:

Fig. l is a somewhat diagrammatic illustration through a vesselcontaining a composition of two substances the ratio of which it isdesired to ascertain,

Fig. 2 is a vertical elevation showing apparatus used in an alkylationprocess, Fig. 3 is a diagram to which reference will be made inexplaining the principles of the invention,

Fig. 4 is an enlarged view through a section o-f pipe showing a somewhatdifferent arrangement o-f the radiation source and detector, while Fig.5 is a sectional plan view through a vessel ,showing an arrangement ofapparatus for con- 3 trolling the proportions of substances of acomposition within the vessel.

In Figure 1 of the drawing a vessel I0 is shown as containing a quantityof a composition I 2 whichmay be a mixture of two substances or anemulsion, solution 01 chemical composition of the two substances. Ahousing or block I 4 of a material such as lead capable of absorbinggamma radiation contains at its inner surface a small amount of aradioactive substance I6, such as radium, and a beam of the penetrativeradiation, indicated diagrammatically by the dotted line 22, istransmitted through the walls of the vessel I and through thecomposition I2. At another side of the vessel I0 is a housing 24containing a suitable detector 26 of penetrative radiation which maycomprise a Geiger-Mller counter, a proportional counter or an ionizationchamber. The detector 26 is connected to a suitable amplier 28, theoutput of which is in turn led to ameasuringA instrument such as themeter 3Q. If desired, a suitable preamplifiermay be disposed within thehousing 24.

With reference to Figure 3 let us assume that the side walls of thevessel III of Figure 1 are denoted by the vertical lines IU and thatthese walls have no appreciable thickness; that the intensity of theincoming radiation beam is indicated at Io and that theintensity of theradiation emerging from the vessel is indicated by I.` Also let usassume that there are two substances a and b in the vessel and thecross-hatched portions indicate the relative proportions of these twosubstances in the path of the beam ofV transmitted radiation. Forpurposes of illustration only, the amount of the substance "a isindicated by the blockv or section marked a as though this substancewere all in one place, likewise that the substance "bv is positioned inone place in alignment with the radiation source and the substance "a.rIfhen the distance a: will designate the proportion of the substance ain the mixture or composition and Z minus a: designates the portion ofthe substance "b, Z of course, indicating the length oi the path of thebeam through the composition.

First let us assume that there is only one substance in the vessel I0'and that the beam of radiation therefore passes through nothing otherthan this substance a and the walls of the vessel. Then,

In Ine-.ICJ

where L is the intensity of the radiation which has passed through thesubstance af and los is the absorption coeicient for the substance afAssuming then that the substance b is the only substance in the path ofthe beam of radiation,

where ks is the absorption coeicient for the s ub.- stance "b.

Let us assume now that both substances are in the vessel as shown inFigure 3 and that I is the intensity of the radiation after it haspassed through the substance a and before it reaches the Substance 11.then From Equations 1, 2 and 5 one can solve for the three unknowns lcs,kb and If l is assumed to be one then x will be the percentage of thesubstance a in the composition do In this discussion We have assumedthat the walls have no thickness. In an actual case where thecomposition is in a container, the equations would obviously include afactor to represent the absorbing effect ofv the walls.

It is to be understood that the substances "a and o Within the path ofthe radiation beam can be mixed in any manner or they can comprise asolution, an emulsion or dispersion, or a chemical combination of thetwo substances since the absorption of the radiation in the compositiondepends only upon the atomic structure. In other words, the absorptionof gamma rays depends only on the number of atoms per unit volume and itremainsunchanged as long as the number of atoms remains the same,regardless of the nature ofthe composition, i. e., whether it is in theform of a mixture, solution, etc.

It will be clear from the above that once the measurements are obtainedfor each substance separately, it will thereafter be necessary merely totake a singlereading on any mixture or solution of these substances andfrom that reading the proportion or ratio of the substances can bequickly determined. If desired, a curvecan be prepared either for thetwo substances separately or for known ratios of the two substances,vand then the ratio of the unknown composition read directly from thecurve. While the container I 0 has been described as a vessel, it iscontemplated that it may be a pipe or conduit through which thecomposition I2 is owing. The pipe should be full so that the length ofthe path of the radiation beam through the composition will not vary.

In Figure 2 the invention is illustrated as applied to the determinationof the ratio ofv the acid catalyst to the hydrocarbons in the emulsionflowing from a contactor of the Stratco type in an alkylation system.The contactor is represented at 32 into which the isoparaiilnichydrocarbons isobutane and butylene enter through the pipe 34. The freshacid-catalyst enters the contactor through the pipes 36 and 38 and amotor 40 serves to drive an agitator, not shown, so as to emulsify theacid and hydrocarbons. The emulsion is drawn from the upper portion ofthe contactor 32 through the pipe 42 and is passed to a separator 44.Part of the acid settling in the separator may be recycled by means ofthe pump 46 through the pipe 38 into the contactor. The pipe 42 isillustrated as having a short vertical section 48 and on the oppositesides of,y this section are placed the housing I4 containing the sourceof radiation and the housing 24 containing the radiation detector. Theoutput of the detector passes to the amplifier 28 and then to the meter30 as has been described hereinbefore. By placing the source and thedetector at opposite sides of a vertical pipe one is assured that thepipe will remain full of the emulsion. Assuming that intensitymeasurements have been made of the acid alone and of the hydrocarbonsalone when occupying the pipe section 48, or that the instrument 30 hasbeen calibrated in any other suitable manner it is then merely necessaryto observe or record the reading of the meter 30 to determine theproportions or the ratio of the acid and the hydrocarbons whentheemulsion is passing through the pipe section 48.

The greater the length ofv the path of the -radiation through thecomposition, the'mor'e accurate `will be the measurements. l Thus, if itis desired to measure density variations oithe order of, say, plus orminus y0.5 Be'., in the emulsion stance, be 'the pipe 48 of Figure 2with the housving I4 containing the source positioned against the outersurface of the pipe and the housing. 2t

` containing a detector 28 positioned adjacent the opposite side of thepipe but ina lower position `with respect to the housing M. The path of.the

beam 22 is therefore increased Vand greater vaccuracy will be'attained.The source must, of course, have sufficient strength to transmitradiation through the desired path 22 to actuate the detector 26.

Figure is a sectional plan view showing a modication in which a housingIlla containing a source of radiation is mounted on the exterior surfaceof a vessel 32a, which may be, for instance, the contactor 32 of Figure2. Also disposed adjacent the exterior of the vessel across, but notnecessarily exactly opposite the housing Ida, is a housing 24acontaining' a radiation detector 26a. The housing 24 is positioned withrespect to the housing Ma so that the radiation beam 22a within theemulsion will be long enough to provide measurements of the desiredaccuracy. In this manner the acid-hydrocarbon ratio of the emulsion 32acan be measured while the emulsion is still being circulated within thevessel.

Although the invention has been described as a method of measuring ordetermining ratios of substances in a composition, it is contemplatedthat these determinations can be used in connection with control inmanufacturing processes. As shown in Figure 5, the vessel `32d isprovided with two intake pipes or conduits 50 and 52, one for each ofthe substances to be treated within the vessel. The conduit 52 isprovided with a valve 54 actuable by suitable means such as a solenoidillustrated diagrammatically at 5S. The output of the detector 26a isconnected to an amplifier 28a the output of which in turn is led to arelay 58. The relay is connected to the solenoid 56 and is adapted inany well known manner to connect a source oi electric current 6B tothesolenoid when the relay is actuated by a predetermined increase ordecrease in the output of the amplifier 28a. Thus, assuming for examplethat isobutane-butylene enters the vessel 32a through the pipe Ell andthat' the acid catalyst enters through the pipe 52, the apparatus shownin Figure 5 can be easily Ladjusted to maintain a desired ratio betweenthese substances in the emulsion within the vessel 32a. In case theratio should change more than an allowable amount, the response of thedetector 26a will change and the amplier output will cause the relay 58to operate to actuate the solenoid 56 to open or close the valve 54, asthe case may be, to control the amount of acid flowing into the vessel32a.

The method is applicable in many other processes such as in continuousgrease lmanufacture to assure uniformity of batches, 1n determining theextent of polymerization iin rubber manufacture, the extent of crackingand the extent of dehydrogenation in dehydro operations, and in thecontrol of fractionation operations, particularly those applied to theseparation of LAmining or measuring of temperature.

source may be advantageous.

6 vmaterial-in high .degree or purity. The `foregoing are by way ofexample only. i rFrom the principles of the invention which have beendescribed in the foregoing paragraphs it will also be observed thatsince the intensity of the radiation beam passing through a` compositionvaries with the density of that composition and since the densityk willvary with changes in temperature in the composition, the invention isalso applicable in the deter- Thus, with reference again tolFigure 2, ifthe meter .Sil is calibrated in temperature and the temperatureof theemulsion passing through the pipe section 43 changes, the density of the.emulsion will change accordingly and the vmeter There is usually'a lagin the action of most temperature sensitive devices such asthermocouples and the like but with the present method `the meter 3l)will respond substantially instantaneously to variations in density ofthe composition within the pipe 43, and thus to variations intemperature.

While the source l5 has been described as radium and the radiation beamas comprising gamma rays, it is to be understood that other types orradiation can be used. For instance, neutrons emitted from a mixture ofradium and berylium could be utilized, the detector 25 in such a casecomprising preferably an ionization chamber or a proportional counter.Likewise, in certain instances an articially radioactive Wherepenetrative radiation is referred to in the claims, it is vcontemplatedthat any of these radiations or others, such as for example, X-rays,alpha rays, electrons and protons can be used.

It is to be understood that in the claims which follow, althoughreference may be made to a specific form of composition such as amixture, it is intended that all other forms of composition are to beincluded Within the meaning of this term, such as solutions, emulsions,suspensions, dispersions, chemical combinations and the like.

Obviously many other modiiications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, but only such limitations should be imposed as areindicated in the appended claims.

I claim:

1. The method of determining the proportions of two substances in amixture which comprises transmitting a beam of electrons through saidmixture over a predetermined path, transmitting said beam throughmixtures of said substances wherein the proportions of the substancesare known while maintaining the length of the path the same as for saidfirst transmission, measuring the intensities of said beam after beingtransmitted through said unknown mixture and said known mixtures, andfrom a comparison of the measurements so obtained calculating Vtheproportions of the substances in the unknown mixture.

2. The method of determining the proportions of two substances in acomposition owing through a .pipe which rcomprises transmittingsubstantially .laterally .through .said pipe a beam ruf electrons when.the pipe is conducting :a composition yof ;said Isubstances fand whenthe pipe ,contains each :substance separately, observing the intensities`of the beam .after it :has .traversed the pipe, and from themeasurements so obtained fcalculatingsaid proportions.

43. The ,method ,of determining the ratio of 4two substances in acomposition which comprises transmitting a -beam of .electrons through-said composition-fandthrough other compositions .of the same substanceswherein .the Aratio of the :substances is known, while 4maintaining`con" :stant the lengths .of the paths of said beam Athrough :the ;knownand `unknown compositions, i'and .measuring the intensities `of the:radiation lafter passing `thrnugh :said compositions, and :from said.measurements .calculating .the proportions of .the substances in the.rst :mentioned :composition .4. The method of determining the4proportions of two substances kin a .mixture ,in `an `opaque container-which comprises transmitting `through .said container -and saidsubstance Va .beamof electrons, repeating this operation when thevcontainer holds mixtures .of said substances in known proportions.observing -the intensities ofthe beam during each transmission', and.from

.the measurements .so obtained, :calculating :said

proportions.

5. The method of Vdeterminingthe proportions of two substances in amixture in an opaque container which comprises transmitting a beam ofelectrons through atleast ,a portion of the mixture in .said container,repeating this opera.- tionwhen .the container Aholds .mixtures of said.substances in known proportions while maintaining the length ofthe path.of said beam .the same :as 'for said Ifirst transmission, observing theYintensities yof the beam .during each transmission, ;andirom themeasurements `so .obtained calculating said proportions.

GERHARD HER/ZOG.

-REFERENCES CITED The following references are of record in the `file ofthis patent:

UNITED STATES PATENTS Number .'Name Date Re. 22,531 Hare Aug. 22, 19.442,487,797 Friedman let al Nov.. V15, 1949 2,534,352 Herzog Dec.l19, 1950

1. THE METHOD OF DETERMINING THE PROPORTIONS OF TWO SUBSTANCES IN AMIXTURE WHICH COMPRISES TRANSMITTING A BEAM OF ELECTRONS THROUGH SAIDMIXTURE OVER A PREDETERMINED PATH, TRANSMITTING SAID BEAM THROUGHMIXTURES OF SAID SUBSTANCES WHEREIN THE PROPORTIONS OF THE SUBSTANCESARE KNOWN WHILE MAINTAINING THE LENGTH OF THE PATH THE SAME AS FOR SAIDFIRST TRANSMISSION, MEASURING THE INTENSITIES OF SAID BEAM AFTER BEINGTRANSMITTED THROUGH SAID UNKNOWN MIXTURE AND SAID KNOWN MIXTURES, ANDFROM A COMPARISON OF THE MEASUREMENTS SO OBTAINED CALCULATING THEPROPORTIONS OF THE SUBSTANCES IN THE UNKNOWN MIXTURE.